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Nelson-Flanders Water Treatment Plant

Total Site

122 acres (49ha)

Treatment Capacity

114,000m³/d expandable to 228,000m³/d; possible further expansion to 300,000m³/d


2-stage rapid mixing, 3-stage flocculation and high-rate lamella plate settlers


6 x deep-bed dual-media filters

Filtration Media

Anthracite / sand

Reservoir Capacity


Raw Water Pipeline

3 x 30in-diameter steel

Treated Water (main City) pipeline

1 x 54in-diameter steel

Additional Treated Water Pipeline

8in-diameter steel

Project Cost


Initial Master Plan Studies

1989 and 1999

Project Initialised

October 1999

1041 Permit Application

June 2001

1041 Granted

October 2001

Contract Awarded

2002 (fourth quarter)

WTP Design Began

January 2003

Pipeline Scheme Design Began

May 2003

WTP Construction Began

August 2003

Pipeline Construction Began

October 2003

First Raw Water Pipe Connections

March 2005

Process Building Finished

April 2005

Reservoir Filled

May 2005

Scheduled Completion (original)

February 2006

Start Up

Late summer 2005

Final Raw Water Pipe Connection

December 2005


City of Longmont

Main Contractor (design and build)

Western Summit / Black & Veatch Joint Venture

Electrical / Instrumentation and Control Contractor

MWI McDade-Woodcock


Greenburg & Greenburg

Pipeline Contractors

Garney Construction / Integra Engineering